heritabilities

Question 1

Vp?

Answer 1

Vp = VG + VE

- variation in phenotype is affected by variation due to genetics and variation due to environment

Question 2

Vg?

Answer 2

Vg = VA + VD + VI
- Genetic variation is affected by variance due to additive genetic effects, dominance genetic variance and interaction variance

Question 3

whats heritability

Answer 3

• quantifying how much variation is genetic
• h^2 = heritability; the square of the correlation coefficient between phenotype and genotype (measures the proportion of variance explained by the correlation)
• heritability is the contribution of genetic variation to the phenotypic variation
• if 0 then all variation is environment
• if 1 then all variation is genetic (never)

Question 4

Broad sense heritability

Answer 4

• H^2 = VG / VP

- determines in broad terms how much genetics determines phenotypic differences

Question 5

Narrow sense heritability

Answer 5

• h^2 = VA / VP
• how much additive (how selective it is) genetics determining phenotypic differences
• determines the outcome of selections

Question 6

heritability equation with selection?

Answer 6

directional selection:
(selection differential) S = mean of selected - mean of before
(selection response) R = new mean - old mean
h^2 = R / S
- we can use this equation to predict yield for next generation

Question 7

calculating heritability from parent / offspring regression?

Answer 7

• the slope is the heritability

y = a + bx (bx = slope)

Question 8

calculating heritability from similarity of related individuals?

Answer 8

• if a character has a high h^2, character = similar within the family
• monozygotic twins h^2 = r

Question 9

what is S?

Answer 9

S = mean of selected - mean of before (the new mean after selection has acted - the 1st mean you started with)
the selection differential

Question 10

what is R?

Answer 10

R = new mean - old mean (the new yield/mean in next gen - the oldest, 1st mean you started with)
the response